The recent detection of gravitational waves together with the discovery, few years ago, of an extraterrestrial component of high-energy neutrinos, inaugurate the era of multimessenger astrophysics.
The relativistic effects owing to the beaming of the jet, that is pointing at us, make blazars the most energetic, persistent particle accelerators of the Universe.
Recent observations show the...
Blazars are a particular class of active galactic nuclei with their relativistic jets pointing close to the line of sight of the observer. Their spectral energy distributions are dominated by non-thermal emission from the jet, consisting of two main bumps. For the so-called extreme blazars, these components each peak in the X-ray and GeV-TeV bands.
Recent observations have revealed that in a...
Active Galactic Nuclei (AGNs) are one of the most studied classes of objects at energies above tens of GeV with current Cherenkov Telescopes and will be a major topic for the upcoming Cherenkov Telescope Array (CTA), the next-generation ground-based gamma-ray observatory. The CTA full array, distributed over two sites, one in the northern and one in the southern hemisphere, will provide...
The term "blazar" refers to a cosmic source with a relativistic jet viewed at a small angle, so that the electromagnetic emission is affected by beaming. Historically, blazars are divided into flat-spectrum radio quasars (FSRQs) and BL Lac Objects (BL Lacs). However, the recent discovery that also Seyfert galaxies (particularly Narrow-Line Seyfert 1 Galaxies, NLS1s) could host powerful...
A rich phenomenology of jets, winds, and accretion states has been observed in both active galactic nuclei (AGN) and X-ray binaries (XRBs), suggesting a connection between the accretion and ejection flows at different black hole masses, from supermassive down to stellar mass.The X-ray emission, associated with the accretion flow, is strongly coupled with the radio emission, associated with a...
